1. Field of the Invention
The present invention, in general, relates to an X-ray and optical analyzing device and, more particularly, to a microscopic X-ray and optical analyzing device for performing material analysis having coaxial viewing and analysis.
2. Description of Related Art
Typically, microscopic X-ray analyzing devices combine an optical microscope with a micro-beam X-ray analyzer for non-destructive sample analysis. This combination allows for elemental imaging analysis such as studying compositional homogeneity of samples. To create an elemental image, a sample is analyzed multiple times, typically as a matrix of points. The individual spectra are incorporated into a database and elemental images are created with pixels calculated based on some property such as X-ray intensity or weight percent. Each image pixel is related to the parent spectrum and a position on the sample.
Prior art microscopic X-ray analyzers position the X-ray beam within an incident angular range of 45°≦θ≦70° to the sample and the camera normal to the sample. However, the positioning of the X-ray beam at such an angle introduces some difficulties in the analysis of a sample. For instance, positioning the sample at a precise distance from the X-ray optic is important so that the incident X-ray beam impinges on the sample at the calibrated position within the sample video field of view. Also, the positioning of an X-ray beam at such an angle produces an elliptical spot, complicating the specification of the beam spot size for the analyst. On the other hand, an X-ray spot will have a simpler circular shape achieving the absolute minimum spot size allowable by the X-ray optic in all directions from the center of the X-ray spot if the X-ray beam is positioned normal (i.e., perpendicular) to the sample.
One solution to the problems of such prior art analyzers is disclosed in U.S. Pat. No. 6,965,663 to Ohzawa. This analyzer irradiates a sample with X-rays narrowed down by an X-ray guide member from above the sample. A mirror is provided to allow an optical image of the sample to be obtained in a direction coaxial with the X-ray guide member. However, this configuration also suffers from various deficiencies. For instance, the mirror used to allow for coaxial imaging of the sample limits the design of the X-ray optics or the number of X-ray optics immediately available to the user. Another problem with such a design is that the use of such a mirror may limit the optical image quality or field of view of the sample.
Another possible design for an analyzer is disclosed in U.S. Pat. No. 6,345,086 to Ferrandino et al. This system includes an X-ray source, X-ray focusing element, and a tapered X-ray opaque focusing aperture that provides a focused X-ray spot on a sample. The system translates a sample between an imaging position and a testing position. In the imaging position, the sample is aligned in three dimensions and, after alignment, the system automatically translates the sample between the imaging position and the testing position. To avoid collision between the sample and other components of the system, a position detecting device terminates the sample translation if the sample trips the position detecting device. Accordingly, this system automatically translates the sample between an imaging position and a testing position. However, the movement of a sample in such a manner may cause a loosely mounted sample to shift while the stage is transitioning between the viewing and analyzing positions.
Accordingly, a need exists for a microscopic X-ray analyzer that allows for coaxial viewing and analyzing of a sample. A further need exists for a microscopic X-ray analyzer that allows for multiple X-ray optics to quickly and easily be placed normal to the sample for analysis without moving the sample.